1. Field of the Invention
The present invention relates to an object detection apparatus for detecting an object from an input image using an image recognition dictionary.
2. Description of Related Art
It is known to perform image recognition based on an image recognition algorithm on an input image obtained by a camera or the like mounted on an own vehicle using an image recognition dictionary describing reference data regarding detection objects for the purpose of detecting an object such as a human or a vehicle present in front or back of the own vehicle. For example, Japanese Patent application Laid-open No. 2010-79716 describes a technique in which an image obtained by an imaging device is collated with template data (recognition dictionary) for detection of a pedestrian.
The recognition dictionary used for detecting a detection object is prepared in advance so as to suit assumed environment conditions. Accordingly, if the actual environmental conditions at the time when the imaging device obtains an image are far apart from the assumed environmental conditions, the robustness of the image recognition performed using the recognition dictionary is degraded, and the detection performance is lowered.
Environment conditions which may affect the detection performance include the distance between the imaging position and a detection object, the brightness, contrast and color of an input image which depend on the solar radiation, weather and time of day. Hence, when the environment conditions vary greatly with time, the performance of object detection performed using the same recognition dictionary may be unstable.